Polyamide resin composition and process for producing the same

ABSTRACT

The present invention provides a polyamide resin composition in which silicate layers originating from a layered silicate and having the below-described property {circle around (1)} are uniformly dispersed on a molecular level in a polyamide resin to accomplish high strength, high modulus, high heat resistance, high toughness, excellent dimensional stability, and high tensile elongation with a small deviation. {circle around (1)}: average particle size from a photograph observation of transmission electron microscopy is 0.1 μm or less and not including a maximum particle size of 30 μm or higher.

FIELD OF THE INVENTION

This invention relates to a polyamide resin composition which providesmolded articles exhibiting high strength, high modulus, high heatresistance, high toughness, excellent dimensional stability and hightensile elongation with small deviation. This invention also relates toa process for producing said polyamide resin composition.

BACKGROUND OF THE INVENTION

Polyamide resin compositions reinforced with fibrous reinforcingmaterials such as glass fiber and carbon fiber or inorganic fillers suchas calcium carbonate are widely known. However, since these reinforcingmaterials have poor affinity to polyamide, the reinforced polyamideresin compositions have reduced toughness while mechanical strength andheat resistance are improved. Furthermore, molded articles of afiber-reinforced polyamide resin composition suffer from appreciablewarp. Additionally, in using the inorganic fillers, substantialimprovement in mechanical strength or heat resistance cannot be obtainedunless they are added in a large quantity.

In order to eliminate these disadvantages of conventional reinforcedpolyamide resin compositions, a composition comprising polyamide and alayered silicate typified by montmorillonite has been proposed(unexamined published Japanese patents No.62-74957, No.63-230766,No.2-102261, and No.3-7729). In this resin composition, silicate layersare uniformly dispersed in the polyamide resin on the molecular level byintroducing polyamide chains into the laminae of a layered silicate. Inthe case of using montmorillonite for the above purpose, themontmorillonite must be swelled with organic salts (e.g., an ammoniumsalt of an aminocarboxylic acid, an onium salt) and then isolated,before the monomer or monomers forming the polyamide resin arepolymerized.

Meanwhile, the present inventors discovered that polyamide resincompositions having a specific layered silicate (swellable fluoromicamineral) uniformly dispersed therein on the molecular level andexhibiting excellent mechanical strength and heat resistance can beobtained without the above-described inorganic salt treatment. This isachieved by mixing monomer(s) forming polyamide and swellable fluoromicamineral, and polymerizing the above-described monomer(s) usually under ahigh pressure of over 10 kg/cm² (unexamined published Japanese patentNo. 6-248176).

Furthermore, the present inventors have proposed a process whichcomprises mixing monomer(s) forming polyamide, swellable fluoromicamineral, and an acid having pKa of 0˜6 or negative (in 25° C. water),and then mixing the above-described monomer(s) (unexamined publishedJapanese patents No.8-3310 and No.8-134205). Because this process doesnot necessarily require high pressure during polymerization,polymerization usually under a pressure of about 5 kg/cm² provides apolyamide resin composition which provides molded articles exhibitingexcellent mechanical strength, toughness, heat resistance, anddimensional stability, low water absorption ratio, and an improved waterabsorption property including no decrease of the above-describedproperties under the influence of water.

However, for the above-described polyamide resin composition, thetensile strength of molded articles is always insufficient and thedeviation of the values is substantially large, being independent of thekind of layered silicates. Moreover, when manufacturing theabove-described polyamide resin composition on an industrial scale, someproblems arise from the viewpoint of productivity including observationof increased pressure at a nozzle part at the withdrawal of the polymerand consequently frequent exchange of filters.

As a result of extensive studies, the present inventors have discoveredthat the above problems are caused by an insufficient degree of uniformdispersion of a layered silicate into a nylon matrix on the molecularlevel, and at the same time by oversized particles which remain in theresin composition originating from impurities contained in a layeredsilicate as a raw material which did not participate in the aboveuniform dispersion.

This invention provides a polyamide resin composition which providesmolded articles exhibiting high strength, high modulus, high heatresistance, high toughness, excellent dimensional stability, and hightensile elongation with small deviation. Also provided is a process forproducing said polyamide resin composition.

SUMMARY OF THE INVENTION

The present invention solves the above-described problems by providing:

(1) A polyamide resin composition in which a layered silicate having thebelow-described property {circle around (1)} is uniformly dispersed on amolecular level.

{circle around (1)}: average particle size from observation oftransmission electron microscope is 0.1 μm or less and does not includea maximum particle size of 30 μm or higher.

(2) The polyamide resin composition according to (1) above, wherein saidpolyamide resin is selected from the group consisting of nylon 6, nylon6 copolymers, nylon 11, nylon 11 copolymers, nylon 12 and nylon 12copolymers.

(3) The polyamide resin composition according to (1) or (2) above,wherein 0.01˜10 parts by weight of the layered silicate having theabove-described property {circle around (1+L )} per 100 parts by weightof said polyamide resin are formulated.

(4) A process for producing the polyamide resin composition described in(3), which comprises polymerizing a monomer forming 100 parts by weightof polyamide resin after mixing with 0.1˜10 parts by weight of a layeredsilicate of the below-described property {circle around (2)} having acation exchange capacity of 50˜200 meq/100 g and an acid (pKa 0˜6 ornegative in 25° C. water) at an amount of 3 times or less moles per thetotal cation exchange capacity of the above-described layered silicate,wherein the total amount of the above-described layered silicate and thetotal amount of the above-described acid are mixed with a fraction ofthe monomer corresponding to 30 wt % or less of the total amount of theabove-described monomer, followed by addition of the rest of the monomerand polymerization of the monomer.

{circle around (2)}: average particle size of 1˜6 μm by laserdiffraction method; not containing particles of 30 μm or larger as amaximum particle size.

(5) A process for producing the polyamide resin composition described in(3), which comprises polymerizing a monomer forming 100 parts by weightof polyamide resin after mixing with 0.1˜10 parts by weight of a layeredsilicate of the above-described property {circle around (2)} having acation exchange capacity of 50˜200 meq/100 g and an acid (pKa 0˜6 ornegative in 25° C. water) at an amount of 3 times or less moles per thetotal cation exchange capacity of the above-described layered silicate.

(6) A process for producing the polyamide resin composition described in(3), which comprises polymerizing a monomer forming 100 parts by weightof polyamide resin after mixing with 0.1˜10 parts by weight of anorganically treated layered silicate which is obtained by a processcomprising (i) mixing a layered silicate of the above-described property{circle around (2)} having a cation exchange capacity of 50˜200 meq/100g, an acid (pKa 0˜6 or negative in 25° C. water) at an amount of 3 timesor less moles per the total cation exchange capacity of theabove-described layered silicate, and a compound forming an organiccation by reacting with the above-described acid in the presence ofwater, and (ii) treating at 60° C. or higher.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 explains how to measure an average particle size from photographobservation by transmission electron microscopy.

DETAILED DESCRIPTION OF THE INVENTION

The following is a detailed description of the present invention.

The polyamide resin composition comprises polyamide having dispersedtherein silicate layers on a molecular level. The language “on amolecular level” as used herein means that the layers of the layeredsilicate are spaced 20 Å or more from each other on average. The spacingbetween layers of the layered silicate is the distance between thecenters of gravity of substantially every layer of a layered silicate.The language “dispersed” as used herein means that individual laminae orlaminates having not more than 5 laminae, on average, of a layeredsilicate are present in parallel with each other and/or at random,wherein 50% or more, preferably 70% or more, of the laminae or laminatesare dispersed without forming masses. More specifically, photographicobservation from transmission electron microscopy (TEM) and evaluationof deviation in tensile elongation measurement can confirm such adispersed state. In the present invention, silicate layers in thepolyamide resin composition should have the above-described property{circle around (1)}: average particle size from observation oftransmission electron microscope is 0.1 μm or less and does not includea maximum particle size of 30 μm or higher, by the method below forevaluating an average particle size and a maximum particle size. Thelanguage “not include a maximum particle size of 30 μm or higher” meansthat no layered silicate having an particle size of 30 μm or higher isobserved in 10 photographs taken by TEM.

The polyamide resin is a polymer having an amide linkage, which isprepared from a monomer such as a lactam or an aminocarboxylic acid, ormonomers such as a diamine and a dicarboxylic acid (or a nylon saltcomprising a pair of them).

Examples of monomers which constitute the polyamide resin include6-aminocaproic acid, 11-aminoundecanoic acid, 12-aminododecanoic acidand p-aminomethylbenzoic acid as an aminocarboxylic acid, and the lactamincludes ε-caprolactam, ω-undecanolactam and ω-laurolactam.

Examples of the diamine include tetramethylenediamine,hexamethylenediamine, undecamethylenediamine, dodecamethylenediamine,2,2,4-/2,4,4-trimethylhexamethylenediamine,5-methylnonamethylenediamine, 2,4-dimethyloctamethylenediamine,m-xylylenediamine, p-xylylenediamine 1,3-bis(aminomethyl)cyclohexane,1-amino-3-aminomethy-3,5-trimethylcyclohexane,bis(4-aminocyclohexyl)methane, bis(3-methyl-4-aminocyclohexyl)methane,2,2-bis(4-aminocyclohexyl)propane, bis(aminopropyl)piperazine andaminoethypiperazine.

Examples of the dicarboxylic acid include adipic acid, suberic acid,azelaic acid, sebacic acid, decanedicarboxylic acid, terephthalic acid,isophthalic acid, naphthalenedicarboxylic acid, 2-chloroterephthalicacid, 2-methyterephthalic acid, 5-methylisophthalic acid,5-sulfoisophthalic acid; sodium salt, hexahydroterephthalic acid,hexahydroisophthalic acid and diglycollic acid. A nylon salt comprisinga pair of a diamine and a dicarboxylic acid can also be used.

Specific examples of the polyamide resin include polycaproamide (nylon6), poly(tetramethylene adipamide) (nylon 46), poly(hexamethyleneadipamide) (nylon 66), poly(hexamethylene sebacamide) (nylon 610),poly(hexamethylene dodecamide) (nylon 612), poly(undecamethyleneadipamide) (nylon 116), polyundecamide (nylon 11), polydodecamide (nylon12), poly(trimethyhexamethylene terephthalamide) (nylon TMDT),poly(hexamethylene isophthalamide) (nylon 61), poly(hexamethyleneterephthal/isophthalamide) (nylon 6T/61),poly[bis(4-aminocyclohexyl)methane dodecamide], (nylon PACM12),poly[bis(3-methyl-4-aminocyclohexyl)methane dodecamide] (nylondimethyPACM12), poly(m-xylylene adipamide), (nylon MXD6),poly(undecamethylene terephthalamide) (nylon 11 T), poly(undecamethylenehexahydroterephthalamide) [nylon 11T(H)], and a copolyamide or mixedpolyamide thereof. Among these, nylon 6, nylon 46 nylon 66, nylon 11,nylon 12, and copolyamides or mixed polymers based on those nylons arepreferred. Nylon 6, nylon 11, nylon 12, and copolymers based on thosepolyamides are especially preferred. The following are examples ofnylon-6 copolymers, nylon-11 copolymers and nylon-12 copolymers.

A nylon-6 copolymer has caproamide units of 80 mole % or more, and isobtained by copolymerizing 80 mole % or more of ε-caprolactam or6-aminocaproic acid and less than 20 mole % of other monomer(s)(lactams, aminocarboxylic acids, or nylon salts) as a comonomer. Thecopolymer preferably has a relative viscosity ranging from 1.5 to 5.0 asmeasured at a concentration of 1 g/dl in 96 wt % concentrated sulfuricacid at 25° C.

Examples of such nylon-6 copolymers include nylon 6/46 (tetramethyleneadipamide) copolymer, nylon 6/66 (hexamethylene adipamide) copolymer,nylon 6/610 (hexamethylene sebacamide) copolymer, nylon 6/612(hexamethylene dodecamide) copolymer, nylon 6/116 (undecamethyleneadipamide) copolymer, nylon 6/11 (undecamide) copolymer, nylon 6/12(dodecamide) copolymer, nylon 6/TMHT (trimethylhexamethyleneterephthalamide) copolymer, nylon 6/6 l (hexamethylene isophthalamide)copolymer, nylon 6/6T (hexamethylene terephthalamide) /6 l(hexamethylene isophthalamide) copolymer, nylon 6/PACM12[bis(4-aminocyclohexyl)methane dodecamide) copolymer, nylon 6/DMPACM12[bis(3-methyl-4-aminocyclohexyl)methane dodecamide) copolymer, nylon6/MXD6 (m-xylylene adipamide) copolymer, nylon 6/11T (undecamethyleneterephthalamide) copolymer and nylon 6/11T(H) (undecamethylenehexahydroterephthalamide) copolymer. Among these copolymers, nylon 6/46copolymer, nylon 6/66 copolymer, nylon 6/11 copolymer and nylon 6/12copolymer are preferred. Nylon 6/66 copolymer and nylon 6/12 copolymerare especially preferred.

A nylon-11 copolymer has undecamide units of 80 mole % or more, and isobtained by copolymerizing 80 mole % or more of 11-aminoundecanoic andless than 20 mole % of other monomer(s) (lactams, aminocarboxylic acids,or nylon salts) as a comonomer. The copolymer preferably has a relativeviscosity ranging from 1.5 to 5.0 as measured at a concentration of 1g/dl in 96 wt % concentrated sulfuric acid at 25° C.

Examples of such nylon-11 copolymers include nylon 11/46 (tetramethyleneadipamide) copolymer, nylon 11/66 (hexamethylene adipamide) copolymer,nylon 11/610 (hexamethylene sebacamide) copolymer, nylon 11/612(hexamethylene dodecamide) copolymer, nylon 11/116 (undecamethyleneadipamide) copolymer, nylon 11/12 (dodecamide) copolymer, nylon 11/TMHT(trimethylhexamethylene terephthalamide) copolymer, nylon 11/6 l(hexamethylene isophthalamide) copolymer, nylon 11/6T (hexamethyleneterephthalamide)/6 l (hexamethylene isophthalamide) copolymer, nylon11/PACM12 [bis(4-aminocyclohexyl)methane dodecamide) copolymer, nylon11/DMPACM12 [bis(3-methyl-4-aminocyclohexyl)methane dodecamide)copolymer, nylon 11/MXD6 (m-xylylene adipamide) copolymer, nylon 11/11T(undecamethylene terephthalamide) copolymer and nylon 11/11T(H)(undecamethylene hexahydroterephthalamide) copolymer. Among thesecopolymers, nylon 11/46 copolymer, nylon 11/66 copolymer, nylon 11/6copolymer and nylon 11/12 copolymer are preferred. Nylon 11/66 copolymerand nylon 11/6 copolymer are especially preferred.

A nylon-12 copolymer has dodecamide units of 80 mole % or more, and isobtained by copolymerizing 80 mole % or more of ε-laurolactam or12-aminododecanoic acid and less than 20 mole % of other monomer(s)(lactams, aminocarboxylic acids, or nylon salts) as a comonomer. Thecopolymer preferably has a relative viscosity ranging from 1.5 to 5.0 asmeasured at a concentration of 1 g/dl in 96 wt % concentrated sulfuricacid at 25° C.

Examples of such nylon-12 copolymers include nylon 12/46 (tetramethyleneadipamide) copolymer, nylon 12/66 (hexamethylene adipamide) copolymer,nylon 12/610 (hexamethylene sebacamide) copolymer, nylon 12/612(hexamethylene dodecamide) copolymer, nylon 12/116 (undecamethyleneadipamide) copolymer, nylon 12/11 (undecamide) copolymer, nylon 12/6(caproamide) copolymer, nylon 12/TMHT (trimethylhexamethyleneterephthalamide) copolymer, nylon 12/6 l (hexamethylene isophthalamide)copolymer, nylon 12/6T (hexamethylene terephthalamide) /6 l(hexamethylene isophthalamide) copolymer, nylon 12/PACM12[bis(4-aminocyclohexyl)methane dodecamide) copolymer, nylon 12/DMPACM12[bis(3-methyl-4-aminocyclohexyl)methane dodecamide) copolymer, nylon12/MXD6 (m-xylylene adipamide) copolymer, nylon 12/11T (undecamethyleneterephthalamide) copolymer and nylon 12/11T(H) (undecamethylenehexahydroterephthalamide) copolymer. Among these copolymers, nylon 12/46copolymer, nylon 12/66 copolymer, nylon 12/11 copolymer and nylon 12/6copolymer are preferred. Nylon 12/66 copolymer and nylon 12/6 copolymerare especially preferred.

The polyamide resin preferably has a relative viscosity ranging from 1.5to 5.0 as measured at a concentration of 1 g/dl in 96 wt % concentratedsulfuric acid at 25° C. If it is less than 1.5, the mechanical strengthin the form of molded articles decreases. If it is more than 5.0, themoldability decreases remarkably.

The layered silicate for use in the present invention has a layerstructure made up of negatively charged laminae mainly comprising asilicate and alkali metal cations therebetween which areion-exchangeable.

The layered silicate also has the above-described property {circlearound (2)}.

The preferred cation exchange capacity of the layered silicate rangesfrom 50 to 200 meq/100 g as measured by the method described below. Ifit is less than 50 meq/100 g, exfoliation of the layered silicate may beinsubstantial during polymerization. If it is more than 200 meq/100 g,the bond between layers is so firm that the layered silicate tends to bedifficult to exfoliate.

Preferred examples of the layered silicate include: those from smectitegroup minerals (montmorillonite, beidellite, saponite, hectorite,sauconite etc); those from vermiculite group minerals (vermiculite etc);those from mica group minerals (fluoromica, muscovite, paragonitephlogopite, biotite, lepidolite, etc); those from brittle mica groupminerals (margarite, clintonite, anandite, etc); and those from chloritegroup minerals (donbassite, sudoite, cookeite, clinochlore, chamosite,nimite, etc).

Those layered silicates are either naturally occurring or synthetic.Swellable fluoromica mineral and montmorillonite are preferably used inthis invention.

The swellable fluoromica mineral, most preferred for its whiteness, isrepresented by the following formula, and is readily synthesized.

α(MF)·β(aMgF₂·bMgO)·γSiO₂

(wherein M represents sodium or lithium; α, β, γ, a, and b eachrepresents a coefficient satisfying 0.1≦a≦2, 2≦β≦3.5, 3≦γ≦4, 0≦a≦1,0≦b≦1, and a+b=1).

Such swellable fluoromica mineral can be synthesized by, for example, aso-called melting method which comprises completely melting a mixture ofsilicon oxide, magnesium oxide and various fluorides in an electric ovenor gas oven at 1400 to 1500° C., and cooling the melt to crystallize aswellable fluoromica mineral and allowing the crystals to grow.

The swellable fluoromica mineral can also be obtained by a methodcomprising heating a mixture of talc and alkali fluoride or alkalisilicofluoride in a porcelain crucible at 700 to 1200° C. for a shorttime to intercalate alkali metal ion into the spacings of the talclaminae (as disclosed in unexamined published Japanese patentNo.2-149415). The amount of alkali fluoride or alkali silicofluoridethat is mixed with the talc is preferably in a range of from 10 to 35 wt% based on the mixture. If it is out of this range, the production yielddecreases.

The production of the swellable fluoromica mineral can be confirmed by awide-angle X-ray diffractometry analysis in which a peak correspondingto the thickness of the swellable fluoromica mineral is within 12 to 13Å as the alkali metal ion intercalation proceeds.

The alkali metal of the alkali fluoride or the alkali silicofluorideshould be sodium or lithium, which may be used singly or in combination.When used as the alkali metal, potassium fails to provide a swellablefluoromica mineral, but could be used in a limited amount in combinationwith sodium and/or lithium for the purpose of swelling control. Theswelling can also be controlled by adding a small amount of alumina tothe mixture.

In the case of the swellable fluoromica mineral obtained by the aboveintercalation process of the alkali metal, talc as a raw material notparticipating in intercalation or a needle-like crystal as by-productmay exist in a swellable fluoromica mineral, usually in an amount ofseveral percents by weight. These materials do not participate inuniform dispersion into the polyamide matrix at all, and remain asoversized particles in the polyamide resin composition. Therefore, suchoversized particles should be eliminated by classification or crushing,by which process the swellable fluoromica mineral comes to satisfy theabove-described property ({circle around (2)}. In order to balancebetween elongation property and strength/modulus, it is preferred to usesuch a layered silicate that has an average particle size of 2.5˜6 μmand that does not contain particles of 20 μm or more as maximum.

The above-described montmorillonite has Na⁺ or Ca²⁺ as ion-exchangeablepositive charges. If it occurs naturally, the content ratio of thosecations varies depending on the place of the production. It is preferredthat the cation between the layers of montmorillonite is in advancereplaced by Na⁺ by ion-exchange treatment. Impurities, etc. contained inmontmorillonite should be eliminated by elutriation. Moreover, theparticle size of the montmorillonite is controlled, if necessary, byclassification or crushing in order to meet the above-described property{circle around (2)}. The preferred montmorillonite is such that it hasan average particle size of 1˜3 μm and does not contain a maximumparticle size of 10 μm or more by laser diffraction method in order toprovide balance in elongation property and strength/modulus.

The amount of the layered silicate in the present polyamide resincomposition is preferably 0.1˜10 parts by weight, more preferably 0.5˜5parts by weight per monomer forming 100 parts by weight of polyamideresin. If the amount is less than 0.1 parts by weight, the reinforcingeffect of the layered silicate to the polyamide resin matrix isinsubstantial for obtaining a polyamide resin composition havingexcellent mechanical strength and heat resistance. If it is more than 10parts by weight, the elongation properties of the polyamide resincomposition deteriorate, and molded articles cannot be obtained withmechanical strength and heat resistance in balance.

The following are some processes for producing the present polyamideresin composition.

In a first method, the total amount of the above-described range of thelayered silicate (having the above-described property {circle around(2)} and the total amount of the acid are in advance added to a portionof the monomer for forming a polyamide resin and mixed, followed byaddition of the rest of monomer and then the polymerization.

The amount of monomer that is in advance mixed with the total amount ofthe layered silicate and the acid is preferably 30 wt % or less to thetotal monomer forming the polyamide resin. If the amount exceeds 30 wt%, the elongation enhancement effect tends to decrease in moldedarticles obtained from the present polyamide resin composition. Inconducting the above-described mixing of raw materials prior topolymerization, it is preferable to use an agitating tool such as ahomogenizer to obtain high revolution and high shear, or to use asupersonic radiator, or to treat in an autoclave.

The acid for use in this invention satisfies pKa of 0˜6 or negative (in25° C. water). If the pKa exceeds 6, improvement in mechanical strengthor heat resistance is not substantial because of reduced proton release.

Useful acids, either organic or inorganic, include benzoic acid, sebacicacid, formic acid, acetic acid, monochloroacetic acid, trichloroaceticacid, trifluoroacetic acid, nitrous acid, phosphoric acid, phosphorousacid, hydrochloric acid, hydrobromic acid, hydroiodic acid, nitric acid,sulfuric acid, perchloric acid, fluorosulfonic acid-pentafluoroantimony(1:1) (available from Aldrich under the trade name of Magic Acid®) andfluoroantimonic acid.

The addition amount of the acid is preferably 3 moles or less, morepreferably, 0.5 to 2 moles, per mole of the cation exchange capacity ofthe layered silicate as a raw material. If the acid addition amountexceeds 3 moles per mole of the cation exchange capacity, thepolymerization degree of the polyamide resin tends to be difficult toincrease and also corrosion of the autoclave may occur in production inseries.

The polymerization is preferably conducted at a temperature of 240 to300° C. and a pressure of 2 to 30 kg/cm² for 1 to 15 hours.

A second method comprises mixing monomer forming a polyamide resin inthe above-described range in the presence of a layered silicatesatisfying the above-described property {circle around (2)} and an acid(pKa 0˜6 or negative in 25° C. water) in an amount of 3 moles or lessper the total cation exchange capacity of the above-described layeredsilicate, and then polymerizing the above-described monomer.

The polymerization is preferably conducted at a temperature of 240 to300° C. and a pressure of 2 to 30 kg/cm² for 1 to 15 hours.

The addition amount of the acid is preferably 3 or less moles, morepreferably, 0.5 to 2 moles, per mole of the cation exchange capacity ofthe above-described layered silicate. If the acid addition amountexceeds 3 moles per mole of the cation exchange capacity, it tends to bedifficult to increase the polymerization degree of the polyamide resin,and also corrosion of the autoclave may occur in production in series.

A third method comprises polymerizing a monomer forming 100 parts byweight of polyamide resin after mixing with an organically treatedlayered silicate within the above range, which is obtained by a processcomprising mixing (i)a layered silicate having the above-describedproperty {circle around (2)}, an acid (pKa 0˜6 or negative in 25° C.water) in an amount of 3 times or less moles per the total cationexchange capacity of the above-described layered silicate, and acompound forming an organic cation by reacting with the above-describedacid in the presence of water, and (ii)treating at 60° C. or higher.

The polymerization is preferably conducted at a temperature of 240 to300° C. and a pressure of 2 to 30 kg/cm² for 1 to 15 hours.

The organically treated layered silicate thus obtained may be under anycondition of water coexistence which includes an aqueous solution and aswelled form, or under a dried condition after isolation. In conductingthe above-described ion exchange treatment, it is preferable to use anagitating tool such as a homogenizer to obtain high revolution and highshear, or to use a supersonic radiator, or to treat in an autoclave.(Hereinafter, a swellable fluoromica mineral that is organically treatedis referred to as an “organic fluoromica”, and montmorillonite which isorganically treated is referred to as “organic montmorillonite”).

Organic compounds which can react with the above-described acids to formorganic cations include those derived from aminocarboxylic acidsrepresented by the following formula {circle around (3)}, lactamsrepresented by the following formula {circle around (4)}, phosphinesrepresented by the following formula {circle around (5)}, and sulfidesrepresented by the following formula {circle around (6)}.Aminocarboxylic acids and lactams are preferred.

[wherein R¹, R², R³, R⁴, and R⁵ are substituents selected from the groupconsisting of alkyl having 1 to 20 carbon atoms, carboxyl, hydroxyl,phenyl, hydrogen atom, where a hydrogen atom in the alkyl or the phenylmay be substituted by a substituent selected from the group consistingof halogen, hydroxyl, carboxyl, —COOR (R is alkyl having 1 to 5 carbonatoms); n represents an integer of 1 to 20; and m represents an integerof 5 to 20.]

Examples of the aminocarboxylic acids include 6-aminocaproic acid,10-aminodecanoic acid, 11-aminoundecanoic acid, 12-amiondodecanoic acidand 18-aminostearic acid. Examples of the lactams include ε-caprolactam,ω-undecanolactam and ω-laurolactam.

The polyamide resin composition can contain various additives, such asheat stabilizers, antioxidants, reinforcing agents, pigments, weatheringagents, flame retardants, plasticizers, mold release agents, and thelike, as long as the properties of the present invention are notimpaired. These additives are added to the polymerization system orwhile the polyamide resin composition is melt-kneaded or melt-molded.

Suitable heat stabilizers or antioxidants include hindered phenols,phosphorus compounds, hindered amines, sulfur compounds, coppercompounds, alkali metal halides, and mixtures thereof.

Suitable reinforcing agents include clay, talc, calcium carbonate, zinccarbonate, wollastonite, silica, alumina, magnesium oxide, calciumsilicate, sodium aluminate, sodium aluminosilicate, magnesium silicate,glass balloons, carbon black, zeolite, hydrotalcite, metal fiber, metalwhiskers, ceramic whiskers, potassium titanate whiskers, boron nitride,graphite, glass fiber and carbon fiber.

The polyamide resin composition can be mixed with other thermoplastics.In this case, the polymers are blended into the polyamide resincomposition when melt-kneaded or melt-molded. Polymers which can beblended into the polyamide resin composition include elastomers such aspolybutadiene, butadiene/styrene copolymers, acrylic rubber,ethylene/propylene copolymers, ethylene/propylene/diene copolymers,natural rubber, chlorinated butyl rubber and chlorinated polyethylene,and acid-modified elastomers (e.g., maleic anhydridemodified-elastomer), styrene/maleic anhydride copolymers,styrene/phenylmaleimide copolymers, polyethylene, polypropylene,butadiene/acrylonitrile copolymers, poly(vinyl chloride), poly(ethyleneterephthalate), polyacetal, poly(vinylidene fluoride), polysulfone,poly(phenylene sulfide), poly(ether sulfone), phenoxy resins,poly(phenylene ether), poly(methyl methacrylate), poly(ether ketone),polycarbonate, polytetrafluoroethylene and polyarylate.

The polyamide resin composition of the present invention can be moldedusing heat-melting molding methods such as injection molding, extrusionmolding, blow molding, and sintering molding. The molded articles thusobtained have highly improved mechanical properties, heat resistance anddimensional stability over those obtained from a polyamide resin alone,and exhibit a low change in mechanical properties and dimension underthe influence of water absorption. Moreover, molded articles of thepresent invention have higher tensile elongation and a small deviationof its values. The molded articles are suitable for housings ormechanical parts (e.g., switches, connectors) in the electric andelectronics fields, underhood and exterior parts, chassis parts, oroptical parts (e.g., reflectors) in the automobile field, and gears orbearing retainers in the machinery fields.

The polyamide resin composition of the present invention can beconverted into films or sheets by general methods such as a tubularmethod, T-die casting method or solution casting method. Such films orsheets thus obtained are excellent in mechanical property, heatresistance, dimensional stability, and also gas barrier property.

The polyamide resin composition also can be converted into fibers by aconventional process comprising, for example, melt-spinning, drawing,and, if necessary, additional heat-setting. The fibers thus obtainedexhibit excellent strength and modulus and also have a small heatshrinkage in a dry state or in boiling water. Such properties aresuitable for various forms such as a circle, hollow, and star-like crosssection so as to keep their shape.

The present invention will be now illustrated in greater detail withreference to the following Examples. However, the present inventionshould not be construed as being limited thereto. The raw materials thatwere used are as follows.

1. Raw Materials

(1) Swellable Fluoromica Mineral

A mixture of 85 wt % of talc having been ground in a ball mill to anaverage particle size of 4 μm and 15 wt % of sodium silicofluoridehaving the same average particle size was placed in a porcelain crucibleand reacted at 850° C. for 1 hour in an electric oven. The resultingpowder was analyzed by wide-angle X-ray diffractometry with a RigakuRAD-rB diffractometer. As a result, the peak corresponding to athickness of 9.2 Å in the c-axis direction of the starting talcdisappeared, and a peak corresponding to 12 to 13 Å was observed, whichindicated the production of swellable fluoromica mineral.

The powder was then crushed with a jet mill (a Nippon Pneumatic PJM-200)at an air pressure of 2 to 3 kg/cm², while oversized particles wereeliminated by passing through a 400 mesh sieve.

If average particle size and maximum particle size are not within theprescribed ranges by the particle size measurement described below,crushing by the jet-mill and elimination of oversized particles bysieving are repeated to adjust an average particle size and maximumparticle size of swellable fluoromica mineral.

The cation exchange capacity of swellable fluoromica mineral thusobtained was 70 meq/100 g according to the method described below.

(2)Montmorillonite

Kunipia F, a highly purified montmorillonite available from KunimineKogyo K. K., naturally occurring in Yamagata, Japan (with intercalatedNa ions) was used after purifying by elutriation.

Based on the result of particle size measurement, jet-milling andsieving to eliminate oversized particles were conducted, as needed.

The cation exchange capacity of the montmorillonite was 115 meq/100 gaccording to the method described below.

2. Measurement Methods

(a) Cation Exchange Capacity of Swellable fluoromica mineral (meq/100 g)

Measured by the method of Frank O. Jones, Jr. (cf. Clay Handbook, 2ndEd. p.587 Gihodo Publishing, 1987). In a 250 ml flask, 50 ml of 2 wt %swellable fluoromica mineral aqueous dispersion, 15 ml of 3 wt % aqueoushydroperoxide, and 0.5 ml of 5N sulfuric acid are mildly boiled for 10minutes. After cooling, 0.5 ml of 1/100N methylene blue solution isadded to the mixture while shaking thoroughly for 30 seconds. Onedroplet of the mixture is taken from the flask with a glass stick,dripped onto a filter paper, and then checked as to whether or not abright blue ring appears around a dark blue spot. A 0.5 ml portion ofthe methylene blue solution is repeatedly added until the blue ringappears. When it appears, the flask is shaken for 2 minutes and thepaper is again dripped. If the ring disappears after shaking, then themethylene blue solution is added until the ring does not disappear. Theend point is established at the point when the ring does not disappeareven after shaking for 2 minutes.

Cation exchange capacity of the swellable fluoromica mineral iscalculated using the following equation:

Cation Exchange Capacity (meq/100 g)=[amount of added methylene blue(meq)]×100/[amount of swellable fluoromica mineral used (g)]

Because all the interlayer cations of the swellable fluoromica mineralconstitute sodium, 1 meq/100 g of the CEC equals 1 mmol/100 g.

(b) Cation Exchange Capacity of Montmorillonite (meq/100 g)

Measured in accordance with a standard method for cation exchangecapacity for bentonite (powder) regulated by the Japan BentoniteAssociation (JBAS-106-77).

In an apparatus equipped with an elution vessel, elution tube andreceiving vessel connected in line, substantially all the cations(mainly Na⁺) between the laminae of montmorillonite are substituted withNH₄ ⁺ using a 1 N ammonium acetate aqueous solution, the pH of which isadjusted to 7. After thoroughly washing with water and ethanol, thelayered silicate in NH₄ ⁺ form is soaked in a 10 wt % potassium chloridesolution to replace NH₄ ⁺ in the sample by K⁺. The cation exchangecapacity (meq/100 g) of the starting montmorillonite is determined bytitrating the eluted NH₄ ⁺ with 0.1 N sodium hydroxide solution.

(c) Particle Size Distribution of Layered Silicates as Raw Materials(Average Particle Size, Maximum Particle Size)

Measured with a Shimadzu SALD-2000 particle size distribution analyzer(laser diffraction scattering method) equipped with a flow-cell inmethanol as a medium.

(d) Particle Size Distribution of Layered Silicates in Polyamide ResinComposition (Average Particle Size, Maximum Particle Size)

As shown in FIG. 1, an ultra-thin slice is cut out from a perpendicularplane to the flow direction of the resin in a bending test specimen.Length in a long-axis direction of silicate layers in a dispersed stateis measured by using photographs taken by transmission electronmicroscopy (TEM) (Type JEM-200CX, acceleration voltage 100 kV, by JapanElectrics) at a magnification of 60,000. The average particle size ofsilicate layers is defined as an arithmetic mean of measured sizes ofarbitrarily selected 50 silicate layers contained in 10 TEM photographstaken from different parts. The maximum particle size is defined as amaximum layer size measured in the same 10 photographs.

(e) Relative Viscosity of Polyamide Resin Composition

Dried pellets of polyamide resin composition are dissolved in 96%sulfuric acid at a concentration of 1 g/dl. The measurement is done at25° C.

(f) Tensile Strength, Tensile Modulus, and Tensile Elongation at Break

Measured in accordance with ASTM D-638.

(g) Flexural Strength and Flexural Modulus

Measured in accordance with ASTM D-790.

(h) Izod Impact Strength

Measured on a notched specimen having a thickness of 3.2 mm inaccordance with ASTM D-256.

(i) Heat Distortion Temperature

Measured in accordance with ASTM D-648 (load: 1.86 MPa).

EXAMPLE 1

1 kg of ε-caprolactam (corresponding to 10 wt % of the total monomer)was dissolved into 2 kg of water, and 200 g of swellable fluoromicamineral (average particle size 3.8 μm, maximum particle size 20 μm bylaser diffraction method; total cation exchange capacity correspondingto 0.14 mole) and 16.1 g of 85 wt % phosphoric acid (0.14 mole) wereadded and agitated for one hour to obtain a mixture. The mixture wasintroduced into a 30 liter-volume reactor which was in advance chargedwith 9 kg of ε-caprolactam. The temperature and the pressure were thenelevated to 260° C. and 5 kg/cm², respectively. The reaction system wasmaintained at a temperature of 260° C. and a pressure of 5 kg/cm² for 2hours to conduct polymerization while gradually releasing steam,followed by pressure release to atmospheric pressure over a 1 hourperiod. After standing under conditions of atmospheric pressure and 260°C. for 40 minutes, the reaction mixture was withdrawn in strands, cooledto solidify, and cut to obtain pellets of polyamide-6 resin composition.The pellets were refined in 95° C. hot water for 8 hours and then driedin vacuo. The resulting pellets were injection molded in an injectionmolding machine (125/75MS Model, manufactured by Mitsubishi HeavyIndustries, Ltd.) at a cylinder temperature of 260° C. and a moldtemperature of 70° C. for an injection time of 6 seconds and a coolingtime of 6 seconds to prepare 3.2 mm thick specimens for testing.

EXAMPLE 2

1 kg of ε-caprolactam (corresponding to 10 wt % of the total monomer)was dissolved into 2 kg of water, and 200 g of montmorillonite (averageparticle size 1.3 μm, maximum particle size 10 μm by laser diffractionmethod; total cation exchange capacity corresponding to 0.23 mole) and26.5 g of 85 wt % phosphoric acid (0.23 mole) were added and agitatedfor 1 hour to obtain a mixture. The mixture was introduced into a 30liter-volume reactor which was in advance charged with 9 kg ofε-caprolactam. Pellets of polyamide-6 resin composition were obtained inthe same manner as in Example 1. The pellets after being refined anddried were injection molded in the same manner as in Example 1 toprepare 3.2 mm thick specimens for testing.

EXAMPLE 3

2 kg of ε-caprolactam (corresponding to 20 wt % of the total monomer)were dissolved into 2 kg of water, and 200 g of swellable fluoromicamineral (average particle size 3.8 μm, maximum particle size 20 μm bylaser diffraction method; total cation exchange capacity correspondingto 0.14 mole) and 16.1 g of 85 wt % phosphoric acid (0.14 mole) wereadded and agitated for 1 hour to obtain a mixture. The mixture wasintroduced into a 30 liter-volume reactor which was in advance chargedwith 8 kg of ε-caprolactam. Pellets of polyamide-6 resin compositionwere obtained in the same manner as in Example 1. The pellets afterbeing refined and dried were injection molded in the same manner as inExample 1 to prepare 3.2 mm thick specimens for testing.

EXAMPLE 4

2 kg of ε-caprolactam (corresponding to 20 wt % of the total monomer)were dissolved into 2 kg of water, and 200 g of montmorillonite (averageparticle size 1.3 μm, maximum particle size 10 μm by laser diffractionmethod; total cation exchange capacity corresponding to 0.23 mole) and26.5 g of 85 wt % phosphoric acid (0.23 mole) were added and agitatedfor 1 hour to obtain a mixture. The mixture was introduced into a 30liter-volume reactor which was in advance charged with 8 kg ofε-caprolactam. Pellets of polyamide-6 resin composition were obtained inthe same manner as in Example 1. The pellets after being refined anddried were injection molded in the same manner as in Example 1 toprepare 3.2 mm thick specimens for testing.

Comparative Example 1

Pellets of polyamide-6 resin composition were obtained in the samemanner as in Example 1, except that swellable fluoromica mineral havingan average particle size of 5.0 μm and a maximum particle size of 100 μmby laser diffraction method was used. The pellets after being refinedand dried were injection molded in the same manner as in Example 1 toprepare 3.2 mm thick specimens for testing.

Comparative Example 2

Pellets of polyamide-6 resin composition were obtained in the samemanner as in Example 2, except that montmorillonite having an averageparticle size of 1.5 μm and a maximum particle size of 40 μm by laserdiffraction method was used in place of swellable fluoromica mineral.The pellets after being refined and dried were injection molded in thesame manner as in Example 1 to prepare 3.2 mm thick specimens fortesting.

Table 1 summarizes the results obtained in Examples 1 to 4 andComparative Examples 1 to 2.

TABLE 1 Comparative Example No. Example No. 1 2 3 4 1 2 Kind of LayeredSynthetic Mont- Synthetic Mont- Synthetic Mont- Silicate Mica morillo-Mica morillo- Mica morillo- nite nite nite Layered Particle distributionof Silicate layered silicate {circle around (1)} Aver. part. size (μm)3.8 1.3 3.8 1.3 5.0 1.5 Max. part. size (μm) 20 10 20 10 100 40 Contentof oversized 0 0 0 0 1.6 0.8 particle* (%) when charged {circle around(2)} Aver. part. size (μm) 0.08 0.06 0.08 0.05 0.63 0.37 Max. part. size(μm) 0.43 0.28 0.58 0.41 50 27 in PA resin comp. Poly- Kind of Polyamidenylon-6 nylon-6 nylon-6 nylon-6 nylon-6 nylon-6 amide Added amnt. oflayered 2.0 2.0 2.0 2.0 2.0 2.0 Resin silicate (parts by wt.)Composition Relative Viscosity 2.6 2.6 2.6 2.6 2.6 2.6 PropertiesTensile strength (MPa) 91 92 88 88 86 85 of Tensile modulus 3100 31003050 3150 2850 2900 Specimen Tensile elongation (%) 66 84 58 79 11 33Flexural strength (MPa) 153 158 149 156 166 162 Flexural modulus (MPa)4200 4250 4150 4200 4400 4350 Izod impact strength (J/m) 63 66 62 64 4643 Heat distortion, temp. (° C.) 147 153 142 151 109 120 *particle sizeof 30 μm or more by laser diffraction method

EXAMPLE 5

10 kg of ε-caprolactam, 200 g of swellable fluoromica mineral (averageparticle size 3.8 μm, maximum particle size 20 μm by laser diffractionmethod; total cation exchange capacity corresponding to 0.14 mole), 16.1g of 85 wt % phosphoric acid (0.14 mole), and 2 kg of water wereintroduced into a 30 liter-volume reactor and agitation was started. Thetemperature and the pressure were then elevated to 260° C. and 5 kg/cm²,respectively. The reaction system was maintained at a temperature of260° C. and a pressure of 5 kg/cm² for 2 hours to conduct polymerizationwhile gradually releasing steam, followed by pressure release toatmospheric pressure over a 1 hour period. After standing underconditions of atmospheric pressure and 260° C. for 40 minutes, thereaction mixture was withdrawn in strands, cooled to solidify, and cutto obtain pellets of polyamide 6 resin composition. The pellets afterbeing refined and dried were injection molded in the same manner as inExample 1 to prepare 3.2 mm thick specimens for testing.

EXAMPLE 6

200 kg of ε-caprolactam, 8 kg of swellable fluoromica mineral (averageparticle size 3.8 μm, maximum particle size 20 μm by laser diffractionmethod; total cation exchange capacity corresponding to 5.6 moles),645.6 g of 85 wt % phosphoric acid (5.6 moles), and 6.6 kg of water wereintroduced into a 500 liter-volume reactor. The temperature and thepressure were then elevated to 260° C. and 5 kg/cm², respectively, whileagitating. The reaction system was maintained at a temperature of 260°C. and a pressure of 5 kg/cm² for 2 hours to conduct polymerizationwhile gradually releasing steam, followed by pressure release toatmospheric pressure over a 1 hour period. After standing underconditions of atmospheric pressure and 260° C. for 40 minutes, thereaction mixture was withdrawn in strands from a nozzle equipped with 2sheets of 240 mesh filter, cooled to solidify, and cut to obtain pelletsof polyamide 6 resin composition. Meanwhile pressure increase in thenozzle section was monitored.

The pellets were refined in 95° C. hot water for 8 hours and then driedin vacuo. The resulting pellets were injection molded in an injectionmolding machine (125/75MS Model, manufactured by Mitsubishi HeavyIndustries, Ltd.) at a cylinder temperature of 260° C. and a moldtemperature of 70° C. for an injection time of 6 seconds and a coolingtime of 6 seconds to prepare 3.2 mm thick specimens for testing.

EXAMPLE 7

200 kg of ε-caprolactam, 8 kg of montmorillonite (average particle size1.3 μm, maximum particle size 10 μm by laser diffraction method; totalcation exchange capacity corresponding to 9.2 moles), 1060.7 g of 85 wt% phosphoric acid (9.2 moles), and 6.6 kg of water were introduced intoa 500 liter-volume reactor. Pellets of polyamide-6 resin compositionwere obtained in the same manner as in Example 5, while pressureincrease in the nozzle section (equipped with 2 sheets of 240 meshfilter) was monitored.

The pellets after being refined and dried were injection molded in thesame manner as in Example 5 to prepare 3.2 mm thick specimens fortesting.

Comparative Example 3

Pellets of polyamide-6 resin composition were obtained in the samemanner as in Example 6, except that swellable fluoromica mineral havingan average particle size of 5.0 μm and a maximum particle size of 100 μmby laser diffraction method was used. Pressure increase in the nozzlesection (equipped with 2 sheets of 240 mesh filter) was monitored.

The pellets after being refined and dried were injection molded in thesame manner as in Example 5 to prepare 3.2 mm thick specimens fortesting.

Comparative Example 4

Pellets of polyamide-6 resin composition were obtained in the samemanner as in Comparative Example 7, except that montmorillonite havingan average particle size of 1.5 μm and a maximum particle size of 40 μmby laser diffraction method was used. Pressure increase in the nozzlesection (equipped with 2 sheets of 240 mesh filter) was monitored.

The pellets after being refined and dried were injection molded in thesame manner as in Example 5 to prepare 3.2 mm thick specimens fortesting.

Table 2 summarizes the results obtained in Examples 5 to 7 andComparative Examples 3 to 4.

TABLE 2 Comparative Example No. Example No. 5 6 7 3 4 Kind of LayeredSynthetic Synthetic Mont- Synthetic Mont- Silicate Mica Mica morillo-Mica morillo- nite nite Layered Particle distribution of Silicatelayered silicate {circle around (1)} Aver. part. size (μm) 3.8 3.8 1.35.0 1.5 Max. part. size (μm) 20 20 10 100 40 Content of oversized 0 0 01.6 0.8 particle* (%) when charged {circle around (2)} Aver. part. size(μm) 0.08 0.09 0.09 0.68 0.42 Max. part. size (μm) 0.62 0.48 0.36 55 34in PA resin comp. Poly- Kind of Polyamide nylon-6 nylon-6 nylon-6nylon-6 nylon-6 amide Added amnt. of layered 2.0 4.0 4.0 4.0 4.0 Resinsilicate (parts by wt.) Composition Relative Viscosity 2.6 2.6 2.6 2.62.6 Properties Tensile strength (MPa) 82 84 85 81 82 of Tensile modulus3050 3150 3100 3200 2900 Specimen Tensile elongation (%) 56 36 75 9 25Flexural strength (MPa) 147 150 155 169 158 Flexural modulus (MPa) 41504250 4200 4350 4200 Izod impact strength (J/m) 64 58 62 46 42 Heatdistortion, temp. (° C.) 142 148 150 118 122 *particle size of 30 μm ormore by laser diffraction method

EXAMPLE 8

10 kg of 11-aminoundecanoic acid, 200 g of swellable fluoromica mineral(average particle size 3.8 μm, maximum particle size 20 μm by laserdiffraction method; total cation exchange capacity corresponding to 0.14mole) and 16.1 g of 85 wt % phosphoric acid (0.14 mole) were introducedinto a 30 liter-volume reactor. The temperature was then elevated to220° C. and polymerization was conducted under nitrogen for 2 hours. Thereaction mixture was withdrawn in strands, cooled to solidify, and cutto obtain pellets of polyamide-11 resin composition. The pellets afterbeing dried were injection molded in an injection molding machine(125/75MS Model, manufactured by Mitsubishi Heavy Industries, Ltd.) at acylinder temperature of 230° C. and a mold temperature of 70° C. for aninjection time of 6 seconds and a cooling time of 10 seconds to prepare3.2 mm thick specimens for testing.

EXAMPLE 9

10 kg of 11-aminoundecanoic acid, 400 g of swellable fluoromica mineral(average particle size 3.8 μm, maximum particle size 20 μm by laserdiffraction method; total cation exchange capacity corresponding to 0.28mole) and 32.3 g of 85 wt % phosphoric acid (0.28 mole) were introducedinto a 30 liter-volume reactor. Pellets of polyamide-11 resincomposition were obtained in the same manner as in Example 8. Thepellets after being dried were injection molded in the same manner as inExample 8 to prepare 3.2 mm thick specimens for testing.

EXAMPLE 10

10 kg of 11-aminoundecanoic acid, 200 g of montmorillonite (averageparticle size 1.3 μm, maximum particle size 10 μm by laser diffractionmethod; total cation exchange capacity corresponding to 0.23 mole) and26.5 g of 85 wt % phosphoric acid (0.23 mole) were introduced into a 30liter-volume reactor. The temperature was then elevated to 220° C. andpolymerization was conducted under nitrogen for 2 hours. Pellets ofpolyamide-11 resin composition were obtained in the same manner as inExample 8. The pellets after being dried were injection molded in thesame manner as in Example 8 to prepare 3.2 mm thick specimens fortesting.

Comparative Example 5

Pellets of polyamide-11 resin composition were obtained in the samemanner as in Example 8, except that swellable fluoromica mineral havingan average particle size of 5.0 μm and a maximum particle size of 100 μmby laser diffraction method was used. The pellets after being dried wereinjection molded in the same manner as in Example 8 to prepare 3.2 mmthick specimens for testing.

Comparative Example 6

Pellets of polyamide-11 resin composition were obtained in the samemanner as in Example 10, except that montmorillonite having an averageparticle size of 1.5 μm and a maximum particle size of 40 μm by laserdiffraction method was used. The pellets after being dried wereinjection molded in the same manner as in Example 8 to prepare 3.2 mmthick specimens for testing.

Table 3 summarizes the results obtained in Examples 8 to 10 andComparative Examples 5 to 6.

TABLE 3 Comparative Example No. Example No. 8 9 10 5 6 Kind of LayeredSynthetic Synthetic Mont- Synthetic Mont- Silicate Mica Mica morillo-Mica morillo- nite nite Layered Particle distribution of Silicatelayered silicate {circle around (1)} Aver. part. size (μm) 3.8 3.8 1.35.0 1.5 Max. part. size (μm) 20 20 10 100 40 Content of oversized 0 0 01.6 0.8 particle* (%) when charged {circle around (2)} Aver. part. size(μm) 0.09 0.08 0.07 0.70 0.46 Max. part. size (μm) 0.89 0.93 0.41 63 39in PA resin comp. Poly- Kind of Polyamide nylon-11 nylon-11 nylon-11nylon-11 nylon-11 amide Added amnt. of layered 2.0 4.0 2.0 2.0 2.0 Resinsilicate (parts by wt.) Composition Relative Viscosity 2.6 2.6 2.6 2.62.6 Properties Tensile strength (MPa) 59 63 60 58 57 of Tensile modulus2100 2150 2050 2050 2000 Specimen Tensile elongation (%) 173 128 189 144152 Flexural strength (MPa) 75 79 74 83 77 Flexural modulus (MPa) 22502450 2200 2400 2300 Izod impact strength (J/m) 66 57 70 58 60 Heatdistortion, temp. (° C.) 71 82 69 57 55 *particle size of 30 μm or moreby laser diffraction method

EXAMPLE 11

10 kg of ω-laurolactam, 200 g of swellable fluoromica mineral (averageparticle size 3.8 μm, maximum particle size 20 μm by laser diffractionmethod; total cation exchange capacity corresponding to 0.14 mole), 16.1g of 85 wt % phosphoric acid (0.14 mole) and 1.5 kg of water wereintroduced into a 30 liter-volume reactor. The temperature and pressurewere then elevated to 280° C., 22 kg/cm², respectively. The reactionsystem was maintained at a temperature of 290˜300° C. and a pressure of22 kg/cm² for 12 hours to conduct polymerization while graduallyreleasing steam, followed by pressure release to atmospheric pressureover a 1 hour period. After standing under conditions of atmosphericpressure for 40 minutes, the reaction mixture was withdrawn in strands,cooled to solidify, and cut to obtain pellets of polyamide-12 resincomposition. The pellets after being dried were injection molded in aninjection molding machine (125/75MS Model, manufactured by MitsubishiHeavy Industries, Ltd.) at a cylinder temperature of 230° C. and a moldtemperature of 70° C. for an injection time of 6 seconds and a coolingtime of 10 seconds to prepare 3.2 mm thick specimens for testing.

EXAMPLE 12

10 kg of ω-laurolactam, 400 g of swellable fluoromica mineral (averageparticle size 3.8 μm, maximum particle size 20 μm by laser diffractionmethod; total cation exchange capacity corresponding to 0.28 mole), 32.3g of 85 wt % phosphoric acid (0.28 mole) and 1.5 kg of water wereintroduced into a 30 liter-volume reactor. Pellets of polyamide-12 resincomposition were obtained in the same manner as in Example 11. Thepellets after being dried were injection molded in the same manner as inExample 11 to prepare 3.2 mm thick specimens for testing.

EXAMPLE 13

10 kg of ω-laurolactam, 200 g of montmorillonite (average particle size1.3 μm, maximum particle size 10 μm by laser diffraction method; totalcation exchange capacity corresponding to 0.23 mole), 26.5 g of 85 wt %phosphoric acid (0.23 mole), and 1.5 kg of water were introduced into a30 liter-volume reactor. Pellets of polyamide-12 resin composition wereobtained in the same manner as in Example 11. The pellets after beingdried were injection molded in the same manner as in Example 11 toprepare 3.2 mm thick specimens for testing.

Comparative Example 7

Pellets of polyamide-12 resin composition were obtained in the samemanner as in Example 11, except that swellable fluoromica mineral havingan average particle size of 5.0 μm and a maximum particle size of 100 μmby laser diffraction method was used. The pellets after being dried wereinjection molded in the same manner as in Example 11 to prepare 3.2 mmthick specimens for testing.

Comparative Example 8

Pellets of polyamide-12 resin composition were obtained in the samemanner as in Example 13, except that montmorillonite having an averageparticle size of 1.5 μm and a maximum particle size of 40 μm by laserdiffraction method was used. The pellets after being dried wereinjection molded in the same manner as in Example 11 to prepare 3.2 mmthick specimens for testing.

Table 4 summarizes the results obtained in Examples 11 to 13 andComparative Examples 7 to 8.

TABLE 4 Comparative Example No. Example No. 11 12 13 7 8 Kind of LayeredSynthetic Synthetic Mont- Synthetic Mont- Silicate Mica Mica morillo-Mica morillo- nite nite Layered Particle distribution of Silicatelayered silicate {circle around (1)} Aver. part. size (μm) 3.8 3.8 1.35.0 1.5 Max. part. size (μm) 20 20 10 100 40 Content of oversized 0 0 01.6 0.8 particle* (%) when charged {circle around (2)} Aver. part. size(μm) 0.09 0.09 0.08 0.76 0.45 Max. part. size (μm) 1.2 0.98 0.39 71 40in PA resin comp. Poly- Kind of Polyamide nylon-12 nylon-12 nylon-12nylon-12 nylon-12 amide Added amnt. of layered 2.0 4.0 2.0 2.0 2.0 Resinsilicate (parts by wt.) Composition Relative Viscosity 2.6 2.6 2.6 2.62.6 Properties Tensile strength (MPa) 60 63 59 56 55 of Tensile modulus2000 2300 1950 2050 2050 Specimen Tensile elongation (%) 141 135 166 120132 Flexural strength (MPa) 75 93 78 88 86 Flexural modulus (MPa) 22502400 2300 2350 2350 Izod impact strength (J/m) 68 55 67 54 55 Heatdistortion, temp. (° C.) 73 81 71 56 55 *particle size of 30 μm or moreby laser diffraction method

EXAMPLE 14

200 g of swellable fluoromica mineral (average particle size 3.8 μm,maximum particle size 20 μm by laser diffraction method; total cationexchange capacity corresponding to 0.14 mole) were added to a premixedsolution containing 15.8 g of ε-caprolactam (0.14 mole), 10 kg of water,and 16.1 g of 85 wt % phosphoric acid (0.14 mole). The mixturecontaining organic fluoromica was obtained after agitating at 70° C. for60 minutes with a homogenizer. Organic fluoromica was recovered byrepeated filtering and washing with a Buchner funnel, then dried andcrushed.

190 g of the above-described organic fluoromica were introduced into a30 liter-volume reactor which was in advance charged with 10 kg ofε-caprolactam and 1 kg of water. The temperature and the pressure werethen elevated to 260° C. and 5 kg/cm², respectively. The reaction systemwas maintained at a temperature of 260° C. and a pressure of 5 kg/cm²for 2 hours to conduct polymerization while gradually releasing steam,followed by pressure release to atmospheric pressure over a 1 hourperiod. After standing under conditions of atmospheric pressure and 260°C. for 40 minutes, the reaction mixture was withdrawn in strands, cooledto solidify, and cut to obtain pellets of polyamide-6 resin composition.The pellets were refined in 95° C. hot water for 8 hours and then driedin vacuo. The resulting pellets were injection molded in an injectionmolding machine (125/75MS Model, manufactured by Mitsubishi HeavyIndustries, Ltd.) at a cylinder temperature of 260° C. and a moldtemperature of 70° C. for an injection time of 6 seconds and a coolingtime of 10 seconds to prepare 3.2 mm thick specimens for testing.

EXAMPLE 15

200 g of swellable fluoromica mineral (average particle size 1.3 μm,maximum particle size 100 μm by laser diffraction method; total cationexchange capacity corresponding to 0.23 mole) were added to a premixedsolution containing 26.0 g of ε-caprolactam (0.23 mole), 10 kg of water,and 26.5 g of 85 wt % phosphoric acid (0.23 mole). The mixturecontaining organic montmorillonite was obtained after agitating at 70°C. for 60 minutes with a homogenizer. Organic montmorillonite wasrecovered by repeated filtering and washing with a Buchner funnel, thendried and crushed.

190 g of the above-described organic montmorillonite were introducedinto a 30 liter-volume reactor which was in advance charged with 10 kgof ε-caprolactam and 1 kg of water. Pellets of polyamide-6 resincomposition were obtained in the same manner as in Example 14. Thepellets after being refined and dried injection molded in the samemanner as in Example 14 to prepare 3.2 mm thick specimens for testing.

EXAMPLE 16

A solution containing 1 kg of ε-caprolactam (corresponding to 10 wt % ofthe total monomer) and 2 kg of water, 200 g of swellable fluoromicamineral (average particle size 3.8 μm, maximum particle size 20 μm bylaser diffraction method; total cation exchange capacity correspondingto 0.14 mole), and 16.1 g of 85 wt % phosphoric acid (0.14 mole) weremixed. The mixture containing organic fluoromica was obtained afteragitating at 70° C. for 60 minutes with a homogenizer.

The above mixture was introduced into a 30 liter-volume reactor whichwas in advance charged with 9 kg of ε-caprolactam. Pellets ofpolyamide-6 resin composition were obtained in the same manner as inExample 14. The pellets after being refined and dried were injectionmolded in the same manner as in Example 14 to prepare 3.2 mm thickspecimens for testing.

EXAMPLE 17

A solution containing 1 kg of ε-caprolactam (corresponding to 10 wt % ofthe total monomer) and 2 kg of water, 200 g of montmorillonite (averageparticle size 1.3 μm, maximum particle size 10 μm by laser diffractionmethod; total cation exchange capacity corresponding to 0.23 mole), and26.5 g of 85 wt % phosphoric acid (0.23 mole) were mixed. The mixturecontaining organic montmorillonite was obtained after agitating at 70°C. for 60 minutes with a homogenizer.

The above mixture was introduced into a 30 liter-volume reactor whichwas in advance charged with 9 kg of ε-caprolactam. Pellets ofpolyamide-6 resin composition were obtained in the same manner as inExample 14. The pellets after being refined and dried were injectionmolded in the same manner as in Example 14 to prepare 3.2 mm thickspecimens for testing.

Comparative Example 9

Pellets of polyamide-6 resin composition were obtained in the samemanner as in Example 14, except that swellable fluoromica mineral havingan average particle size of 5.0 μm and a maximum particle size of 100 μmby laser diffraction method was used. The pellets after being dried wereinjection molded in the same manner as in Example 14 to prepare 3.2 mmthick specimens for testing.

Comparative Example 10

Pellets of polyamide-6 resin composition were obtained in the samemanner as in Example 15, except that montmorillonite having an averageparticle size of 1.5 μm and a maximum particle size of 40 μm by laserdiffraction method was used. The pellets after being dried wereinjection molded in the same manner as in Example 14 to prepare 3.2 mmthick specimens for testing.

Comparative Example 11

Pellets of polyamide-6 resin composition were obtained in the samemanner as in Example 16, except that swellable fluoromica mineral havingan average particle size of 5.0 μm and a maximum particle size of 100 μmby laser diffraction method was used. The pellets after being dried wereinjection molded in the same manner as in Example 14 to prepare 3.2 mmthick specimens for testing.

Comparative Example 12

Pellets of polyamide-6 resin composition were obtained in the samemanner as in Example 17, except that montmorillonite having an averageparticle size of 1.5 μm and a maximum particle size of 40 μm by laserdiffraction method was used. The pellets after being dried wereinjection molded in the same manner as in Example 14 to prepare 3.2 mmthick specimens for testing.

Table 5 summarizes the results obtained in Examples 14 to 17 andComparative Examples 9 to 12.

TABLE 5 Example No. Comparative Example No. 14 15 16 17 9 10 11 12 Kindof Layered Synthetic Mont- Synthetic Mont- Synthetic Mont- SyntheticMont- Silicate Mica morillo- Mica morillo- Mica morillo- Mica morillo-nite nite nite nite Layered Particle distribution of Silicate layeredsilicate {circle around (1)} Aver. part. size (μm) 3.8 1.3 3.8 1.3 5.01.5 5.0 1.5 Max. part. size (μm) 20 10 20 10 100 40 100 40 Content ofoversized 0 0 0 0 1.6 0.8 1.6 0.8 particle* (%) when charged {circlearound (2)} Aver. part. size (μm) 0.04 0.04 0.07 0.03 0.22 0.28 0.310.28 Max. part. size (μm) 0.21 0.21 0.38 0.13 35 33 42 33 in PA resincomp. Poly- Kind of Polyamide nylon-6 nylon-6 nylon-6 nylon-6 nylon-6nylon-6 nylon-6 nylon-6 amide Added amnt. of layered 2.0 2.0 2.0 2.0 2.02.0 2.0 2.0 Resin silicate (parts by wt.) Composition Relative Viscosity2.6 2.6 2.6 2.6 2.6 2.6 2.6 2.6 Properties Tensile strength (MPa) 93 9394 92 86 84 85 87 of Tensile modulus 3250 3200 3150 3150 2900 2850 28502800 Specimen Tensile elongation (%) 107 135 95 121 22 78 14 57 Flexuralstrength (MPa) 154 161 156 164 167 167 169 159 Flexural modulus (MPa)4300 4200 4350 4250 4500 4550 4600 4250 Izod impact strength (J/m) 65 6466 65 48 47 50 51 Heat distortion, temp. (° C.) 155 151 150 155 111 110110 109 *particle size of 30 μm or more by laser diffraction method

EXAMPLE 18

200 g of swellable fluoromica mineral (average particle size 3.8 μm,maximum particle size 20 μm by laser diffraction method; total cationexchange capacity corresponding to 0.14 mole) were added to a premixedsolution containing 28.1 g of 11-aminoundecanoic acid (0.14 mole), 10 kgof water, and 16.1 g of 85 wt % phosphoric acid (0.14 mole). The mixturecontaining organic fluoromica was obtained after agitating at 70° C. for60 minutes with a homogenizer. Organic fluoromica was recovered byrepeated filtering and washing with a Buchner funnel, then dried andcrushed.

190 g of the above-described organic fluoromica were introduced into a30 liter-volume reactor which was in advance charged with 10 kg of11-aminoundecanoic acid. The temperature was then elevated to 220° C.and polymerization was conducted under nitrogen for 2 hours. Thereaction mixture was withdrawn in strands, cooled to solidify, and cutto obtain pellets of polyamide-11 resin composition. The pellets wereinjection molded in an injection molding machine (125/75MS Model,manufactured by Mitsubishi Heavy Industries, Ltd.) at a cylindertemperature of 230° C. and a mold temperature of 70° C. for an injectiontime of 6 seconds and a cooling time of 10 seconds to prepare 3.2 mmthick specimens for testing.

EXAMPLE 19

200 g of montmorillonite (average particle size 1.3 μm, maximum particlesize 10 μm by laser diffraction method; total cation exchange capacitycorresponding to 0.23 mole) were added to a premixed solution containing46.2 g of 11-aminoundecanoic acid (0.23 mole), 10 kg of water, and 26.5g of 85 wt % phosphoric acid (0.23 mole). The mixture containing organicmontmorillonite was obtained after agitating at 70° C. for 60 minuteswith a homogenizer. Organic montmorillonite was recovered by repeatedfiltering and washing with a Buchner funnel, then dried and crushed.

Pellets of polyamide-11 resin composition were obtained in the samemanner as in Example 18. The pellets after being dried were injectionmolded in the same manner as in Example 18 to prepare 3.2 mm thickspecimens for testing.

Comparative Example 13

Pellets of polyamide-11 resin composition were obtained in the samemanner as in Example 18, except that swellable fluoromica mineral havingan average particle size of 5.0 μm and a maximum particle size of 100 μmby laser diffraction method was used. The pellets after being dried wereinjection molded in the same manner as in Example 18 to prepare 3.2 mmthick specimens for testing.

Comparative Example 14

Pellets of polyamide-11 resin composition were obtained in the samemanner as in Example 19, except that montmorillonite having an averageparticle size of 1.5 μm and a maximum particle size of 40 μm by laserdiffraction method was used. The pellets after being dried wereinjection molded in the same manner as in Example 18 to prepare 3.2 mmthick specimens for testing.

Table 6 summarizes the results obtained in Examples 18 to 19 andComparative Examples 13 to 14.

TABLE 6 Comparative Example No. Example No. 19 14 Kind of 18 Mont- 13Mont- Layered Synthetic morillo- Synthetic morillo- Silicate Mica niteMica nite Layered Particle Silicate distribution of layered silicate{circle around (1)}Aver. part. 3.8 1.3 5.0 1.5 size (μm) Max. part. size20 10 100 40 (μm) Content of 0 0 1.6 0.8 oversized particle* (%) whencharged {circle around (2)}Aver. part. 0.04 0.04 0.31 0.25 size (μm)Max. part. size 0.36 0.32 45 35 (μm) in PA resin comp. Poly- Kind ofnylon-11 nylon-11 nylon-11 nylon-11 amide Polyamide Resin Added amnt. of2.0 2.0 2.0 2.0 Compo- layered silicate sition (parts by wt) Relative2.6 2.6 2.6 2.6 Viscosity Proper- Tensile 63 62 58 61 ties of strength(MPa) Speci- Tensile 2350 2300 2200 2100 men modulus Tensile >200 >200113 126 elongation (%) Flexural 79 77 84 88 strength (MPa) Flexural 24002350 2550 2500 modulus (MPa) Izod impact 80 74 60 62 strength (J/m) Heatdistortion. 77 75 58 55 temp. (° C.) *particle size of 30 μm or more bylaser diffraction method

EXAMPLE 20

200 g of swellable fluoromica mineral (average particle size 3.8 μm,maximum particle size 20 μm by laser diffraction method; total cationexchange capacity corresponding to 0.14 mole) were added to a premixedsolution containing 27.6 g of ω-laurolactam (0.14 mole), 10 kg of water,and 16.1 g of 85 wt % phosphoric acid (0.14 mole). The mixturecontaining organic fluoromica was obtained after agitating at 70° C. for60 minutes with a homogenizer. Organic fluoromica was recovered byrepeated filtering and washing with a Buchner funnel, then dried andcrushed.

190 g of the above-described organic fluoromica were introduced into a30 liter-volume reactor which was in advance charged with 10 kg ofω-laurolactam. The temperature and the pressure were then elevated to280° C. and 22 kg/cm², respectively, while agitating. The reactionsystem was maintained at a temperature of 290˜300° C. and a pressure of22 kg/cm² for 12 hours to conduct polymerization while graduallyreleasing steam, followed by pressure release to atmospheric pressureover a 1 hour period. After standing under conditions of atmosphericpressure for 40 minutes, the reaction mixture was withdrawn in strands,cooled to solidify, and cut to obtain pellets of polyamide-12 resincomposition. The pellets after being dried were injection molded in aninjection molding machine (125/75MS Model, manufactured by MitsubishiHeavy Industries, Ltd.) at a cylinder temperature of 230° C. and a moldtemperature of 70° C. for an injection time of 6 seconds and a coolingtime of 10 seconds to prepare 3.2 mm thick specimens for testing.

EXAMPLE 21

200 g of montmorillonite (average particle size 1.3 μm, maximum particlesize 10 μm by laser diffraction method; total cation exchange capacitycorresponding to 0.23 mole) were added to a premixed solution containing45.3 g of ω-laurolactam (0.23 mole), 10 kg of water, and 26.5 g of 85 wt% phosphoric acid (0.14 mole). The mixture containing organicmontmorillonite was obtained after agitating at 70° C. for 60 minuteswith a homogenizer. Organic montmorillonite was recovered by repeatedfiltering and washing with a Buchner funnel, then dried and crushed.

Pellets of polyamide-12 resin composition were obtained in the samemanner as in Example 20. The pellets after being dried were injectionmolded in the same manner as in Example 20 to prepare 3.2 mm thickspecimens for testing.

EXAMPLE 22

A solution containing 1 kg of ω-laurolactam (corresponding to 10 wt % ofthe total monomer) and 1.5 kg of water, 200 g of swellable fluoromicamineral (average particle size 3.8 μm, maximum particle size 20 μm bylaser diffraction method; total cation exchange capacity correspondingto 0.14 mole), and 16.1 g of 85 wt % phosphoric acid (0.14 mole) werecharged into a 30 liter-volume reactor while agitating at 160° C. for 60minutes to prepare a mixture containing organic fluoromica.

The above-described mixture was introduced through a transporting pipeinto a 30 liter-volume reactor which was in advance charged with 9 kg ofω-laurolactam. The temperature and the pressure were then elevated to280° C. and 22 kg/cm², respectively, while agitating. The reactionsystem was maintained at a temperature of 290˜300° C. and a pressure of22 kg/cm² for 12 hours to conduct polymerization while graduallyreleasing steam, followed by pressure release to atmospheric pressureover a 1 hour period. After standing under conditions of atmosphericpressure for 40 minutes, the reaction mixture was withdrawn in strands,cooled to solidify, and cut to obtain pellets of polyamide-12 resincomposition. The pellets after being dried were injection molded in aninjection molding machine (125/75MS Model, manufactured by MitsubishiHeavy Industries, Ltd.) at a cylinder temperature of 230° C. and a moldtemperature of 70° C. for an injection time of 6 seconds and a coolingtime of 10 seconds to prepare 3.2 mm thick specimens for testing.

Comparative Example 15

Pellets of polyamide-12 resin composition were obtained in the samemanner as in Example 20, except that swellable fluoromica mineral havingan average particle size of 5.0 μm and a maximum particle size of 100 μmby laser diffraction method was used. The pellets after being dried wereinjection molded in the same manner as in Example 20 to prepare 3.2 mmthick specimens for testing.

Comparative Example 16

Pellets of polyamide-12 resin composition were obtained in the samemanner as in Example 21, except that montmorillonite having an averageparticle size of 1.5 μm and a maximum particle size of 40 μm by laserdiffraction method was used. The pellets after being dried wereinjection molded in the same manner as in Example 20 to prepare 3.2 mmthick specimens for testing.

Comparative Example 17

Pellets of polyamide-12 resin composition were obtained in the samemanner as in Example 22, except that swellable fluoromica mineral havingan average particle size of 5.0 μm and a maximum particle size of 100 μmby laser diffraction method was used. The pellets after being dried wereinjection molded in the same manner as in Example 20 to prepare 3.2 mmthick specimens for testing.

Table 7 summarizes the results obtained in Examples 20 to 22 andComparative Examples 15 to 17.

TABLE 7 Example No. Comparative Example No. 20 21 22 15 16 17 Kind ofLayered Synthetic Mont- Synthetic Synthetic Mont- Synthetic SilicateMica morillo- Mica Mica morillo- Mica nite nite Layered Particledistribution of Silicate layered silicate {circle around (1)} Aver.part. size (μm) 3.8 1.3 3.8 5.0 1.5 5.0 Max. part. size (μm) 20 10 20100 40 100 Content of oversized 0 0 0 1.6 0.8 1.6 particle* (%) whencharged {circle around (2)} Aver. part. size (μm) 0.04 0.03 0.04 0.290.29 0.30 Max. part. size (μm) 0.35 0.31 0.33 0.42 37 50 in PA resincomp. Poly- Kind of Polyamide nylon-12 nylon-12 nylon-12 nylon-12nylon-12 nylon-12 amide Added amnt. of layered 2.0 2.0 2.0 2.0 2.0 2.0Resin silicate (parts by wt.) Composition Relative Viscosity 2.6 2.6 2.62.6 2.6 2.6 Properties Tensile strength (MPa) 64 63 62 60 62 59 ofTensile modulus 2350 2300 2300 2200 2200 2250 Specimen Tensileelongation (%) >200 >200 183 127 141 126 Flexural strength (MPa) 85 8393 93 94 97 Flexural modulus (MPa) 2400 2400 2400 2650 2550 2750 Izodimpact strength (J/m) 83 72 78 61 63 70 Heat distortion, temp. (° C.) 7871 73 59 58 59 *particle size of 30 μm or more by laser diffractionmethod

TEM photographic observation was conducted for each specimen forflexural strength measurement prepared in Examples 1˜22. The layeredsilicates in the polyamide resins had average particle sizes fallingwithin a range of 0.03˜0.09 μm and contained no particles having amaximum size of 30 μm or more. In all the Examples, the layeredsilicates were confirmed to be uniformly dispersed on the molecularlevel in polyamides.

On the other hand, the average particle sizes of the layered silicatesexceeded 0.1 μm in all the TEM photographs taken for each specimen forflexural strength measurement prepared in Comparative Examples 1˜17,which indicates insufficient uniform dispersion on the molecular level.

The present invention provides a polyamide resin composition whichprovides molded articles exhibiting high strength, high modulus, highheat resistance, high toughness, excellent dimensional stability, andhigh tensile elongation with a small deviation.

What is claimed is:
 1. A polyamide resin composition in which aswellable fluoromica mineral having the below-described property {circlearound (1)} is uniformly dispersed on a molecular level, wherein {circlearound (1)}: average particle size from a photograph observation oftransmission electron microscopy is 0.1 μm or less and not including amaximum particle size of 30 μm or higher.
 2. The polyamide resincomposition according to claim 1, wherein said polyamide resin is oneselected from the group consisting of nylon 6, nylon-6 copolymers, nylon11, nylon-11 copolymers, nylon 12 and nylon-12 copolymers.
 3. Thepolyamide resin composition according to claim 1, wherein 0.1˜10 partsby weight of the swellable fluoromica mineral having the above-describedproperty {circle around (1)} per 100 parts by weight of said polyamideresin are formulated.
 4. The polyamide resin composition according toclaim 2, wherein 0.1˜10 parts by weight of the swellable fluoromicamineral having the above-described property {circle around (1)} per 100parts by weight of said polyamide resin are formulated.
 5. A process forproducing the polyamide resin composition of claim 3, which comprisespolymerizing a monomer forming 100 parts by weight of polyamide resinafter mixing with 0.1˜10 parts by weight of a swellable fluoromicamineral of the below-described property {circle around (2)} having acation exchange capacity of 50˜200 meq/100 g and an acid (pKa 0˜6 ornegative in 25° C. water) in an amount of 3 times or less moles per thetotal cation exchange capacity of the above-described swellablefluoromica mineral, wherein the total amount of the above-describedswellable fluoromica mineral and the total amount of the above-describedacid are mixed with a fraction of the monomer corresponding to 30 wt %or less to the total amount of the above-described monomer, followed byaddition of the rest of the monomer and polymerization of the monomer,wherein {circle around (2)}: average particle size of 1˜6 μm by laserdiffraction method; not containing particles of 30 μm or larger as amaximum particle size.
 6. A process for producing the polyamide resincomposition of claim 4, which comprises polymerizing a monomer forming100 parts by weight of polyamide resin after mixing with 0.1˜10 parts byweight of a swellable fluoromica mineral of the above-described property{circle around (2)} having a cation exchange capacity of 50˜200 meq/100g and an acid (pKa 0˜6 or negative in 25° C. water) in an amount of 3times or less moles per the total cation exchange capacity of theabove-described swellable fluoromica mineral, wherein the total amountof the above-described swellable fluoromica mineral and the total amountof the above-described acid are mixed with a fraction of the monomercorresponding to 30 wt % or less to the total amount of theabove-described monomer, followed by addition of the rest of the monomerand polymerization of the monomer.
 7. A process for producing thepolyamide resin composition of claim 3, which comprises polymerizing amonomer forming 100 parts by weight of polyamide resin after mixing with0.1˜10 parts by weight of a swellable fluoromica mineral of theabove-described property {circle around (2)} having a cation exchangecapacity of 50˜200 meq/100 g and an acid (pKa 0˜6 or negative in 25° C.water) in an amount of 3 times or less moles per the total cationexchange capacity of the above-described swellable fluoromica mineral.8. A process for producing the polyamide resin composition of claim 4,which comprises polymerizing a monomer forming 100 parts by weight ofpolyamide resin after mixing with 0.1˜10 parts by weight of a swellablefluoromica mineral of the above-described property {circle around (2)}having a cation exchange capacity of 50˜200 meq/100 g and an acid (pKa0˜6 or negative in 25° C. water) in an amount of 3 times or less molesper the total cation exchange capacity of the above-described swellablefluoromica mineral.
 9. A process for producing the polyamide resincomposition of claim 3, which comprises polymerizing a monomer forming100 parts by weight of polyamide resin after mixing with 0.1˜10 parts byweight of an organically treated swellable fluoromica mineral which isprepared by a process comprising (i) mixing a swellable fluoromicamineral of the above-described property {circle around (2)} having acation exchange capacity of 50˜200 meq/100 g, an acid (pKa 0˜6 ornegative in 25° C. water) in an amount of 3 times or less moles per thetotal cation exchange capacity of the above-described swellablefluoromica mineral, and a compound forming an organic cation by reactingwith the above-described acid in the presence of water, and (ii)treating at 60° C. or higher.
 10. A process for producing the polyamideresin composition of claim 4, which comprises polymerizing a monomerforming 100 parts by weight of polyamide resin after mixing with 0.1˜10parts by weight of an organically treated swellable fluoromica mineralwhich is prepared by a process comprising (i) mixing a swellablefluoromica mineral of the above-described property {circle around (2)}having a cation exchange capacity of 50˜200 meq/100 g, an acid (pKa 0˜6or negative in 25° C. water) in an amount of 3 times or less moles perthe total cation exchange capacity of the above-described swellablefluoromica mineral, and a compound forming an organic cation by reactingwith the above-described acid in the presence of water, and (ii)treating at 60° C. or higher.